Incorrectly deducted premium

I cancelled an insurance policy with the above mentioned company in August 2015 and confirmation of cancellation was received. They still then proceeded at the beginning of September 2015 to deduct a premium. I then sent them an e-mail on 2 September to query the deduction and was advised that it was referred to the credit department for reversal. Various e-mails were sent to them after the initial e-mail to enquire about the progress of the refund payable in respect of the incorrect deduction. They advised that the refund was referred to the cancellation department and will be paid in the last week of September 2015. The refund was not paid and I again followed up with them in October 2015 to enquire about the refund which has still not been paid they again just advised me that it was sent to the cancellation department with no further information as to when the refund will be paid.